WASHINGTON (Reuters) — The Obama
administration wants to keep the International Space Station, a $100
billion orbital research outpost that is a project of 15 nations, flying
until at least 2024, four years beyond a previous target, NASA said on
Wednesday.

The extension will give the U.S. space agency more time to develop
the technologies needed for eventual human missions to Mars, the
long-term goal of NASA's human space program.

Keeping the station in orbit beyond 2020 also opens a window for
commercial companies and researchers to benefit from hefty U.S.
investment in the outpost.

NASA's costs for operating the station, which flies about 250 miles
above Earth, run about $3 billion a year. About half that sum is
spent on transporting crew and cargo.

"This extension… opens up a large avenue of research onboard
station. It also changes the perspective for the commercial
(transportation) providers. Now they can see a market that extends
to at least 2024," he said.

In addition to commercial U.S. cargo ships and planned passenger
space taxis, companies and research organizations are beginning to
make use of the station's unique microgravity environment to develop
a range of new products and technologies, including medications and
off-the-shelf, shoebox-sized satellites.

Construction of the orbital outpost began in 1998. The prime
partners in the venture, with the United States, include Russia,
Europe, Japan and Canada. It has been permanently staffed by
rotating crews of astronauts and cosmonauts since 2000.

Extending the station "is not a U.S.-only decision," Gerstenmaier
said. "We talk to our partners about this. They want to go forward
with this. It's just working through the government approval," he
said.

"We're prepared to do what we have to do if the partners choose to
take a different path," Gerstenmaier added.

A technical review by prime station contractor Boeing shows the
station's laboratories, structural frame and other hardware are safe
to fly until 2028, program manager John Shannon said earlier on
Wednesday at the opening of an international space exploration and
policy summit.

"If the physical hardware continues to operate the way we believe it
does ... that leaves the door open in the future to extend,"
Gerstenmaier said.

At the end of its life, the station will be steered down into the
atmosphere, where it will incinerate. Re-entry will take place over
an ocean so any surviving debris will not threaten populated areas.

The first of up to six U.S. supply runs to the station this year was
slated for launch on Wednesday, but the flight was canceled due to
extremely high levels of radiation caused by a huge solar flare.

Orbital Sciences Corp, one of two firms hired by NASA to ferry cargo
to the station following the retirement of the space shuttles in
2011, may try to launch its Antares rocket and Cygnus cargo ship on
Thursday. The rocket flies from a commercial spaceport on Wallops
Island, Virginia.